NAME: Edwardsiella tarda
SYNONYM OR CROSS REFERENCE: Bacterium 1483–59, Bartholomew group, Asakusa group Footnote 1, Edwardsiella anguillimortifera.
CHARACTERISTICS: Edwardsiella tarda the family Enterobacteriaceae Footnote 2, Footnote 3. They are Gram-negative, motile, facultatively anaerobic rods that have peritrichous flagella and measure 1 µm in diameter and 2–3 µm in length Footnote 2-Footnote 4. E. tarda is lactose negative, H2S-positive, oxidase-negative, catalase-positive, and has a positive indole reaction Footnote 1-Footnote 3. It produces hemolysin Footnote 5.
PATHOGENICITY/TOXICITY: E. tarda is an opportunistic pathogen in humans. It causes both intestinal and extra-intestinal infections, mainly in individuals with impaired immune systems Footnote 2, Footnote 3, Footnote 6. Gastroenteritis is the most common disease associated with E. tarda, with symptoms ranging from mild secretory enteritis to chronic enterocolitis Footnote 3. Acute gastroenteritis is characterized by five to six loose stools a day, nausea, vomiting, and low-grade fever Footnote 3. Enterocolitis or bacillary dysentery is a more severe manifestation characterized by loose bloody stools, colonic ulcerations, pseudomembranes, and nodularity of the terminal ileum Footnote 3. Extra-gastrointestinal manifestations associated with E. tarda infection are rare and include endocarditis, empyema, hepatobiliary infection, peritonitis, intra-abdominal abscess, osteomyelitis, wound infection, septicemia, bacteremia, urosepsis, and meningitis Footnote 1, Footnote 3, Footnote 7, Footnote 8.
EPIDEMIOLOGY: Gastroenteritis due to E. tarda occurs worldwide, although it is more common in tropical and subtropical areas, where raw fish is consumed Footnote 3. Hepatobiliary diseases, malignancies/cancer and diabetes mellitus are the main risk factors for acquiring extraintestinal E. tarda infections Footnote 1. Gastroenteritis is more common in children and extraintestinal infections are more common in adults Footnote 9.
INFECTIOUS DOSE: Unknown.
INCUBATION PERIOD: Unknown.
COMMUNICABILITY: No reports of human-to-human transmission Footnote 3.
ZOONOSIS: Yes, through contact with infected aquatic animals Footnote 2.
DRUG SUSCEPTIBILITY/RESISTANCE: A strain isolated from a pediatric renal transplant recipient with Edwardsiella tarda gastroenteritis was found to be susceptible to ampicillin, cefotaxime, ceftazidime, piperacillin, and ticarcilla- clavulanate in vitro Footnote 3. E. tarda is also susceptible to tetracyclines, quinolones, antifolates, chloramphenicol, nitrofurantoin, fosfomycin, cephalexin, and gentamycin in vitro Footnote 8, Footnote 11.
DRUG RESISTANCE: Most strains are resistant to colistin, polymixin B, oxacillin, rifampin, fusidic acid, and penicillin Footnote 3, Footnote 8, Footnote 12. Strains resistant to ampicillin, piperacillin, gentamicin, and trimethoprim sulfamethoxazole have also been isolated Footnote 1.
SUSCEPTIBILITY TO DISINFECTANTS: E. tarda is susceptible to 1600 ppm hydrogen peroxide, 11.5% sodium hypochlorite, 800 ppm povidon iodine, 3200 ppm formalin solution, glutaraldehyde, 3200 ppm copper sulfate, quaternary ammonium compounds, didecyl dimethyl ammonium chloride (DDAC), and ortho-dichlorobenzen Footnote 13.
PHYSICAL INACTIVATION: Information specific to Edwardsiella tarda is not available, but most vegetative bacteria are susceptible to moist heat (121°C for at least 15 min) and dry heat (160-170°C for at least 1 hour) Footnote 14. Hemolysin produced by E. tarda is heat labile, and sensitive to proteases Footnote 5. Hemolysin produced by E. tarda can be destroyed by formalin Footnote 5.
SURVEILLANCE: Monitor for symptoms. Diagnosis can be made by isolation and culture of the bacteria from clinical specimens on eosin methylene blur agar (EMB agar), followed by biochemical tests Footnote 1-Footnote 3.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Gastroenteritis caused by E. tarda resolves spontaneously without any antibiotic therapy Footnote 3. Aggressive cases can, however, be treated with amoxicillin (e.g. 80 mg/kg twice daily for 3 days), cotrimoxazole, and cephalosporins Footnote 3. Extraintestinal infections due to E. tarda are treated with antibiotics or surgical intervention (debridement and drainage) Footnote 1.
LABORATORY-ACQUIRED INFECTIONS: None reported.
SOURCE/SPECIMENS: Clinical specimens such as stool; urine; cerebrospinal fluid; intrauterine contents; pus; bile; peritoneal fluid; liver, tubo-ovarian, and intra-abdominal abscess; and blood Footnote 1, Footnote 3, Footnote 7.
PRIMARY HAZARDS: Ingestion, accidental parenteral inoculation, direct contact of wounds with the pathogen Footnote 1.
SPECIAL HAZARDS: None
RISK GROUP CLASSIFICATION: Risk Group 2 Footnote 15.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes Footnote 16.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities Footnote 16.
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up Footnote 16.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism by autoclave, chemical disinfection, gamma irradiation, or incineration before disposing. Footnote 16.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labeled Footnote 16.
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: December 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada
Although the information, opinions and recommendations contained in this Pathogen Safety Data sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2011